Lance Armstrong this week admitted to doping for more than a decade during a cycling career that included seven Tour de France championships.

Armstrong made the admission, after years of vehement denials, at the beginning of an at-times tense interview with Oprah Winfrey, taped Monday at a hotel in Austin, Texas. Part 1 of the interview aired on Winfrey's OWN network Thursday night; Part 2 will air Friday night.

Armstrong answered "yes" to a series of questions by Winfrey about doping and added that he didn't believe that it was "humanly possible" to win the Tour without using banned substances or engaging in blood doping. Armstrong said he began using banned substances in the mid-1990s, around the time he was diagnosed with cancer.

He said that at the time he did not believe he was cheating by taking banned substances; rather, he felt he was on a level playing field. He considered the use of banned substances as routine as "putting air in the tires and water in the bottle."

Armstrong said he did not pressure fellow riders to dope in order to keep up with him, yet at other points in the interview he called himself "arrogant" and a "bully" who needed to win at all costs.

"I'm a flawed character," Armstrong said.

He said his fans have "every right" to feel betrayed and that he will spend the rest of his life trying to make amends.

Armstrong said he was clean when competed in the Tour in 2009 and 2010, four years after he retired from cycling. He did not win in either year.

He said he and Winfrey "wouldn't be sitting here" if he hadn't tried to race again, that he would have had a much better chance of getting away with doping.

He was uncomfortable when Winfrey asked him about the lawsuits, threats, retaliations and verbal attacks he has leveled against his accusers over the years.

"It's a major flaw, and it's a guy who expected to get whatever he wanted and to control every outcome. And it's inexcusable. And when I say there are people who will hear this and never forgive me, I understand that. I do," he said.

Armstrong was stripped of all his titles in the wake of a 1,000-page report by the U.S. Anti-Doping Agency (USADA) last October which included testimony from nearly a dozen former teammates. He also was banned for life from competing in triathlons and other sanctioned events. He also lost nearly all his sponsors and left the Livestrong cancer charity he founded in 1997.

Anti-doping officials have said nothing short of a confession under oath — "not talking to a talk-show host," is how World Anti-Doping Agency director general David Howman put it — could prompt a reconsideration of Armstrong's lifetime ban from sanctioned events.

He's also had discussions with USADA.

Armstrong could provide information that might get his ban being reduced to eight years, according to a person with knowledge of the situation. By then, Armstrong would be 49. He returned to triathlons, where he began his professional career as a teenager, after retiring from cycling in 2011, and has told people he's desperate to get back.

There were very few details about Armstrong's performance-enhancing regimen that would surprise anti-doping officials.

What he called "my cocktail" contained the steroid testosterone and the blood-booster erythropoetein, or EPO, "but not a lot," Armstrong said. That was on top of blood-doping, which involved removing his own blood and weeks later re-injecting it into his system.

Whether the confession will help or hurt Armstrong's bruised reputation and his already-tenuous defense in at least two pending lawsuits, and possibly a third, remains to be seen.

He did not answer directly why he is coming clean now.

"This is too late, too late for probably most people, and that's my fault," he said.